1. Field of the Invention
The present invention relates to a fluid pressure roller jack consisting of an inflatable and collapsible bag adapted to be used as a roller or a jack for lifting heavy weights such as derailed vehicles.
It will be understood that the expression "fluid" used herein will include not only liquid but also gas, though water is primarily used as the fluid to be filled in the roller jack.
2. Description of the Prior Art
Such a kind of fluid pressure roller jack has been used which consists of a rubber bag of a rectangle configuration in its collapsed position, the rubber bag being merely provided with a valve for fluid under pressure getting in and out of the bag therethrough. There are several disadvantages with such a construction. In particular, the bag, particularly a large bag in size, occupies a great space in a plane in its collapsed position despite the fact that the fluid under pressure therein has been completely evacuated, which is troublesome in handling. Also there is a tendency for such bags to be damaged in use, and an article supported on such bags is likely to slip thereon that is, the article is normally supported in unstable condition. Moreover, when the inflated bags are used as rollers, corners extending beyond the ends of the rollers interfere with the rolling of the rollers themselves.